Catalytic domain of the Serine/Threonine Kinase, Cell Cycle-Related Kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. CCRK was previously called p42. It is a Cyclin-Dependent Kinase (CDK)-Activating Kinase (CAK) which is essential for the activation of CDK2. It is indispensable for cell growth and has been implicated in the progression of glioblastoma multiforme. In the heart, a splice variant of CCRK with a different C-terminal half is expressed; this variant promotes cardiac cell growth and survival and is significantly down-regulated during the development of heart failure. The CCRK subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.